Electric switch mechanism



Dec. 31, 1935. A. PALME ELECTRIC SWITCH MECI-IAIIISM Filed March 31,1954 2 Sheets-Sheet l IEvencoT: Art ur a me.

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A. PALME.

ELECTRIC SWITCH MECHANISM Dec. 31, 1935.

Filed March 31, 1934 2 Sheets-Sheet 2 Op P r m e Q T a w m m m B w H 3 7& m

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Patented Dec. 31, 1935 UNITED STATES ELECTRIC SWITCH MECHANISM ArthurPalme, Pittsfield, Mass, assignor to General Electric Company, acorporation of New York Application March 31, 1934, Serial No. 718,391

1 Claim.

My invention relates to electric switch mechanisms and is particularlyapplicable in connection with switches for changing transformer tapconnections. It is often desirable to maintain con- 5 stant voltage onthe secondary circuit of a transformer but changes in the load suppliedby the transformer tend to cause this voltage to vary. Transformers areconsequently commonly provided with winding taps and means for changing10. tap connections to vary the voltage ratio and thus maintain thedesired voltage in the secondary circuit 'under varying load conditions.It is further desirable in many cases that the tap connections bechanged without interrupting the load current 15 supplied by thetransformer. The general object of the invention is to provide animproved elec tric switch mechanism particularly adapted forthesepurposes.

The invention will be more fully explained in 20 the followingdescription taken in connection with the accompanying drawings in whichFig. 1 is a side view, partly in section, of a switch mechanismconstructed in accordance with the inven-- tion and applied inconnection with. a trans- 25 former; Fig. 2 is a front view of theswitch mechanism; and Figs. 3 and 4 are'explanatory circuit diagrams.

Like reference characters indicate similar parts in the differentfigures of the drawings.

30 The transformer l shown in Fig. 1 of the drawings is immersed in aninsulating liquid N in a casing I2. A switch casing I3 is secured overan opening in the side of the transformer casing l I, the back of theswitch casing forming 35 a partition H which is preferably liquid tightbetween the transformer and switch compartments provided by the twocasings.

A switch l4 shown in Figs. 1 and 2 is immersed in an insulating liquidIS in the switch 40 casing |3. The switch l4 includes two fixed contactsl6 and I! on the ends of two conductive rods I8 and I9 respectivelywhich extend through bushings 20 in the partition I4 into thetransformer casing H where they are connected to 45 spaced winding tapsof the transformer In. The switch l4 also includes two movable contacts2| and 22 carried by contact arms 23 and 24 respectively. The contactarm 24 projects from a con-v as but insulated from it by an insulatingbushing 30. An impedance 3|, wound on an insulating spool 32, is mountedon the sleeve 29 and connected between the movable contacts 2| and 22through their contact arms 23 and 24 and sleeves 29 and 25. Theimpedance 3| may be inductive 5,

or not as desired. To avoid resistance between the contact arm 24 andthe conductive rod 28, they are preferably connected by a flexibleconnection 32. Each of the fixed contacts l6 and H is shown as includingtwo contact blades 33 which have contact surfaces projecting into thepaths of the movable contacts 2| and 22 respectively. The sleeves 25 and29 and the impedance 3| are rigidly connected together so that there canbe no relative movement between them and consequent injury to theelectrical connections between the impedance and sleeves. The electricalcircuits of the arrangement which has been described are showndiagrammatically in Fig. 3 where the fixed contacts l6 and H areconnected to taps at one end of the tappet transformer wind ing. Ifdesired, the tappet winding may be formed in two sections as showndiagrammatically in Fig. 4, the fixed contacts [6 and I! being connectedto taps in one section of the winding and the other section of thewinding being connected between the movable contacts 2| and 22 and theoutside terminal of the transformer.

Both of the movable contacts 2! and 22 are normally in contact with oneor the other of the fixed contacts l6 and I1 depending on the desiredvoltage ratio of the transformer l0, both movable contacts being shownon the fixed contact IS in Fig. 1. The movable contacts are operated bytwo electromagnets 34 and 35 with 35 their plungers 36 and 31 connectedby insulating rods or tubes 38 and 39 to spaced ears 40 and 4|projecting from opposite sides of the sleeve 25. The electromagnets 34and 35 may be energized and controlled in any manner and from 40 aremote point if desired. If the electromagnet 35 is energized, it willpull the ear 4| up and rotate the sleeves 25 and 29 to move the movablecontacts 2| and 22 from the fixed contact IE to the fixed contact II. Ifthe other electromagnet 34 is energized, it will similarly pull the Vear 40 up to move the movable contacts 2| and 22 from the fixed contactl'l to the fixed contact IS.

The switch with its impedance 3| is arranged to be operated withoutinterrupting the current flowing through its contacts. In thearrangement shown, the impedance 3| is connected between the two movablecontacts 2| and 22. The two contact blades 33 of each fixed contact arearrangedside by side but the two movable contacts 2| and 22 areangularly displaced about their common axis. Thus, one of the movablecontacts will leave a fixed contact ahead of the other movable contactand will then reach the other fixed contact first. The fixed contacts I6and I! are so spaced that the angularly displaced movable contacts maybridge them for a brief instant while they are moving from one fixedcontact to the other. Assume that the movable contacts 2| .and 22 areboth on the fixed contact l6 as shown most clearly in Fig. 1 and theyare to be moved to the fixed contact H. In this initial position of thecontacts, practically all the current will flow through the movablecontact 22 because the impedance 3| is in series with the other movablecontact 2|. The movable contact 22 first leaves the fixed contact i6breaking the circuit through this movable contact and all the currentthen flows through the movable contact 2| and the impedance 3| Themovable contact then reaches the fixed contact I! and current flowsthrough both movable contacts. The impedance 3| is now connected betweenthe two winding taps of the transformer l0 and the voltage between thetwo taps causes a circulating current in the impedance which should beof such value as to limit this current to a safe value. fixed contact 16and all the current flows through the other movable contact 22. Themovable contact 2| finally reaches the fixed contact I I The movablecontact 2| then leaves the but little current will flow through itbecause of the impedance 3| in series with it. The movable contacts 2|and 22 may be moved back to the fixed contact I6 in similar manner butthe steps will of course be reversed.

The contact arms 23 and 24 with their movable contacts 2| and 22 and theimpedance 3| are all rigidly connected together so that there is neverany relative motion between these parts. Consequently, no flexibility isnecessary in the connections between the impedance and the contacts andthese connections may be short and direct and not liable to injury fromthe movements of the switch parts.

The invention has been explained by describl5 ing and illustrating aparticular form of switch and one application thereof but it will beapparent that changes may be made without departing from the spirit ofthe invention and the scope of the appended claim. i What I claim as newand desire to secure by Letters Patent of the United States, is,

A switch including two fixed contacts, a rotatable contact support, twomovable contacts rigidly secured to said support and angularly dis- 25placed about its axis, an insulating spool surrounding said support, animpedance wound on said spool and electrically connected between saidmovable contacts, and means for rotating said support to move saidmovable contacts alternately from one fixed contact to the other.

ARTHUR PALME.

